The present invention relates to a method for checking vehicle tires during driving.
It is of utmost importance for driving safety that the tires of a motor vehicle be in good condition. Generally the tires are examined by appearance for their further future operational fitness during their seasonal change from summer to winter tires, and then are possibly exchanged for new tires. However, the tires are not always balanced when being changed. The result is that an imbalance appearing at the tire can impair driving safety. It can also occur that the operational fitness of a tire on a vehicle is impaired because of a braking which is too strong or from standing too long in one position; this impairment can possibly be rectified by balancing the tires.
From Stxc3x6cker, Jxc3x6rg, i.a.: Der xe2x80x9cIntelligente Reifenxe2x80x9dxe2x80x94Zwischenergebnisse einer interdisziplinxc3xa4ren Forschungskooperation [The xe2x80x9cIntelligent Tirexe2x80x9dxe2x80x94Intermediate Results of an Inter-disciplinary Research Cooperation] in ATZ Automobiltechnische Zeitschrift 97, 1995, 12, P. 824-832, it is known to equip a tire with an integrated force sensor by which it is possible to detect forces acting upon the tire in three directions, namely, the longitudinal or X direction, the transverse or Y direction and the vertical or Z direction. The signals derived from these detected forces can be supplied to an evaluation unit in which a desired evaluation of the signals is carried out.
The German Published Patent Application No. 196 20 581 describes a further device for ascertaining the rotational behavior of a vehicle wheel.
An object of the present invention is to provide a method for checking vehicle tires during driving, by which a disturbance occurring at the tire can be detected.
The design approach of the present invention utilizes a signal detected by a tire sensor for determining a disturbance occurring at the tire, the amplitude characteristic of the signal being analyzed during one wheel revolution. The amplitude characteristic for the detected signal is advantageously analyzed repeatedly for a number of periods, one period corresponding to one wheel revolution. Furthermore, the analyzed amplitude characteristic can be compared to the amplitude characteristic of a signal produced by a sensor at another tire in order to give plausibility to the test results. The appearance of a disturbance at the tire, e.g. a tire imbalance, can be indicated by a display unit. The display unit can also then indicate advice and recommendations for the driver. In addition, upon detection of a disturbance at the tire, a signal can be supplied to the engine management in order to influence it.
The method of the present invention makes it possible in particular to detect a disturbance or a defect at a tire of a vehicle, for example, a tire imbalance, while driving. A vehicle driver can thereby reliably determine himself whether tires on his vehicle must be changed or balanced, since it can be indicated to him by a display unit.